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Felder-Schmittbuhl MP, Hicks D, Ribelayga CP, Tosini G. Melatonin in the mammalian retina: Synthesis, mechanisms of action and neuroprotection. J Pineal Res 2024; 76:e12951. [PMID: 38572848 DOI: 10.1111/jpi.12951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/09/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024]
Abstract
Melatonin is an important player in the regulation of many physiological functions within the body and in the retina. Melatonin synthesis in the retina primarily occurs during the night and its levels are low during the day. Retinal melatonin is primarily synthesized by the photoreceptors, but whether the synthesis occurs in the rods and/or cones is still unclear. Melatonin exerts its influence by binding to G protein-coupled receptors named melatonin receptor type 1 (MT1) and type 2 (MT2). MT1 and MT2 receptors activate a wide variety of signaling pathways and both receptors are present in the vertebrate photoreceptors where they may form MT1/MT2 heteromers (MT1/2h). Studies in rodents have shown that melatonin signaling plays an important role in the regulation of retinal dopamine levels, rod/cone coupling as well as the photopic and scotopic electroretinogram. In addition, melatonin may play an important role in protecting photoreceptors from oxidative stress and can protect photoreceptors from apoptosis. Critically, melatonin signaling is involved in the modulation of photoreceptor viability during aging and other studies have implicated melatonin in the pathogenesis of age-related macular degeneration. Hence melatonin may represent a useful tool in the fight to protect photoreceptors-and other retinal cells-against degeneration due to aging or diseases.
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Affiliation(s)
- Marie Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Université de Strasbourg, Strasbourg, France
| | - David Hicks
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Christophe P Ribelayga
- Department of Vision Sciences, College of Optometry, University of Houston, Houston, Texas, USA
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, USA
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2
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Duong HA, Baba K, DeBruyne JP, Davidson AJ, Ehlen C, Powell M, Tosini G. Environmental circadian disruption re-programs liver circadian gene expression. bioRxiv 2023:2023.08.28.555175. [PMID: 37693605 PMCID: PMC10491124 DOI: 10.1101/2023.08.28.555175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Circadian gene expression is fundamental to the establishment and functions of the circadian clock, a cell-autonomous and evolutionary-conserved timing system. Yet, how it is affected by environmental-circadian disruption (ECD) such as shiftwork and jetlag, which impact millions of people worldwide, are ill-defined. Here, we provided the first comprehensive description of liver circadian gene expression under normal and after ECD conditions. We found that post-transcription and post-translation processes are dominant contributors to whole-cell or nuclear circadian proteome, respectively. Furthermore, rhythmicity of 64% transcriptome, 98% whole-cell proteome and 95% nuclear proteome is re-written by ECD. The re-writing, which is associated with changes of circadian cis-regulatory elements, RNA-processing and protein trafficking, diminishes circadian regulation of fat and carbohydrate metabolism and persists after one week of ECD-recovery.
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Affiliation(s)
- Hao A. Duong
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta GA 30310
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
| | - Kenkichi Baba
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta GA 30310
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
| | - Jason P. DeBruyne
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta GA 30310
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
| | - Alec J. Davidson
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
| | - Christopher Ehlen
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
| | - Michael Powell
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta GA 30310
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta GA 30310
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310
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3
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Baba K, Suen TC, Goyal V, Stowie A, Davidson A, DeBruyne J, Tosini G. The circadian clock mediates the response to oxidative stress in a cone photoreceptor‒like (661W) cell line via regulation of glutathione peroxidase activity. F1000Res 2022; 11:1072. [PMID: 36405557 PMCID: PMC9639596 DOI: 10.12688/f1000research.125133.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
Background: The mammalian retina contains an autonomous circadian clock that controls many physiological functions within this tissue. Our previous studies have indicated that disruption of this circadian clock by removing Bmal1 from the retina affects the visual function, retinal circuitry, and cone photoreceptor viability during aging. In the present study, we employed a mouse-derived cone photoreceptor‒like cell, 661W, to investigate which molecular mechanisms of the circadian clock may modulate cone photoreceptor viability during aging. Methods: Bmal1 knockout (BKO) cells were generated from 661W cells using the CRISPR/Cas9 gene editing tool. Deletion of Bmal1 from 661W was verified by western blot and monitoring Per2-luc bioluminescence circadian rhythms. To investigate the effect of Bmal1 removal on an oxidative stress challenge, cells were treated with hydrogen peroxide (H 2O 2,1 mM) for two hours and then cell viability was assessed. Cells were also cultured and harvested for gene expression analysis and antioxidant assay. Results: Our data indicated that 661W cells contain a functional circadian clock that mediates the response to an oxidative stress challenge in vitro and that such a response is no longer present in the BKO cell. We also hypothesized that the effect was due to the circadian regulation of the intracellular antioxidant defense mechanism. Our results revealed that in 661W cells, the antioxidant defense mechanism showed time dependent variation , whereas in BKO cells, there was an overall reduction in this antioxidant defense mechanism, and it no longer showed time dependent variation. Conclusions: Our work supported the notion that the presence of a functional circadian clock and its ability to modulate the response to an oxidative stress is the underlying mechanism that may protect cones during aging.
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Affiliation(s)
- Kenkichi Baba
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,
| | - Ting-Chung Suen
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
| | - Varunika Goyal
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
| | - Adam Stowie
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
| | - Alec Davidson
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
| | - Jason DeBruyne
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA,Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, 30310, USA
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Mekbib T, Suen TC, Rollins-Hairston A, Smith K, Armstrong A, Gray C, Owino S, Baba K, Baggs JE, Ehlen JC, Tosini G, DeBruyne JP. "The ubiquitin ligase SIAH2 is a female-specific regulator of circadian rhythms and metabolism". PLoS Genet 2022; 18:e1010305. [PMID: 35789210 PMCID: PMC9286287 DOI: 10.1371/journal.pgen.1010305] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/15/2022] [Accepted: 06/22/2022] [Indexed: 01/05/2023] Open
Abstract
Circadian clocks enable organisms to predict and align their behaviors and physiologies to constant daily day-night environmental cycle. Because the ubiquitin ligase Siah2 has been identified as a potential regulator of circadian clock function in cultured cells, we have used SIAH2-deficient mice to examine its function in vivo. Our experiments demonstrate a striking and unexpected sexually dimorphic effect of SIAH2-deficiency on the regulation of rhythmically expressed genes in the liver. The absence of SIAH2 in females, but not in males, altered the expression of core circadian clock genes and drastically remodeled the rhythmic transcriptome in the liver by increasing the number of day-time expressed genes, and flipping the rhythmic expression from nighttime expressed genes to the daytime. These effects are not readily explained by effects on known sexually dimorphic pathways in females. Moreover, loss of SIAH2 in females, not males, preferentially altered the expression of transcription factors and genes involved in regulating lipid and lipoprotein metabolism. Consequently, SIAH2-deficient females, but not males, displayed disrupted daily lipid and lipoprotein patterns, increased adiposity and impaired metabolic homeostasis. Overall, these data suggest that SIAH2 may be a key component of a female-specific circadian transcriptional output circuit that directs the circadian timing of gene expression to regulate physiological rhythms, at least in the liver. In turn, our findings imply that sex-specific transcriptional mechanisms may closely interact with the circadian clock to tailor overt rhythms for sex-specific needs.
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Affiliation(s)
- Tsedey Mekbib
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Ting-Chung Suen
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Aisha Rollins-Hairston
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Kiandra Smith
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Ariel Armstrong
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Cloe Gray
- Neuroscience Institute, Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Sharon Owino
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Kenkichi Baba
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Julie E. Baggs
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - J. Christopher Ehlen
- Neuroscience Institute, Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Gianluca Tosini
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Jason P. DeBruyne
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
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DeVera C, Dixon J, Chrenek MA, Baba K, Le YZ, Iuvone PM, Tosini G. The Circadian Clock in the Retinal Pigment Epithelium Controls the Diurnal Rhythm of Phagocytic Activity. Int J Mol Sci 2022; 23:5302. [PMID: 35628111 PMCID: PMC9141420 DOI: 10.3390/ijms23105302] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/26/2022] [Accepted: 05/03/2022] [Indexed: 02/04/2023] Open
Abstract
The diurnal peak of phagocytosis by the retinal pigment epithelium (RPE) of photoreceptor outer segments (POS) is under circadian control and believed that this process involves interactions from the retina and RPE. Previous studies have demonstrated that a functional circadian clock exists within multiple retinal cell types and RPE. Thereby, the aim of this study was to determine whether the clock in the retina or RPE controls the diurnal phagocytic peak and whether disruption of the circadian clock in the RPE would affect cellular function and the viability during aging. To that, we generated and validated an RPE tissue-specific KO of the essential clock gene, Bmal1, and then determined the daily rhythm in phagocytic activity by the RPE in mice lacking a functional circadian clock in the retina or RPE. Then, using electroretinography, spectral domain-optical coherence tomography, and optomotor response of visual function we determined the effect of Bmal1 removal in young (6 months) and old (18 months) mice. RPE morphology and lipofuscin accumulation was determined in young and old mice. Our data shows that the clock in the RPE, rather than the retina clock, controls the diurnal phagocytic peak. Surprisingly, absence of a functional RPE clock and phagocytic peak does not result in any detectable age-related degenerative phenotype in the retina or RPE. Thus, our results demonstrate that the circadian clock in the RPE controls the daily peak of phagocytic activity. However, the absence of the clock in the RPE does not result in deterioration of photoreceptors or the RPE during aging.
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Affiliation(s)
- Christopher DeVera
- Department of Pharmacology & Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA; (C.D.); (K.B.)
| | - Jendayi Dixon
- Department of Ophthalmology and Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA; (J.D.); (M.A.C.); (P.M.I.)
| | - Micah A. Chrenek
- Department of Ophthalmology and Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA; (J.D.); (M.A.C.); (P.M.I.)
| | - Kenkichi Baba
- Department of Pharmacology & Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA; (C.D.); (K.B.)
| | - Yun Z. Le
- Departments of Medicine, Cell Biology, and Ophthalmology and Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA;
| | - P. Michael Iuvone
- Department of Ophthalmology and Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA; (J.D.); (M.A.C.); (P.M.I.)
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA; (C.D.); (K.B.)
- Department of Ophthalmology and Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA; (J.D.); (M.A.C.); (P.M.I.)
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6
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Tosini G. Blue-light-blocking Lenses in Eyeglasses: A Question of Timing. Optom Vis Sci 2022; 99:228-229. [PMID: 35058402 PMCID: PMC8897255 DOI: 10.1097/opx.0000000000001866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Gianluca Tosini
- Department of Pharmacology & Neuroscience Institute Morehouse School of Medicine Atlanta, GA
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7
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Baba K, Tosini G. Real-Time Monitoring of Circadian Rhythms in the Eye. Methods Mol Biol 2022; 2550:367-375. [PMID: 36180706 DOI: 10.1007/978-1-0716-2593-4_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The mammalian eye harbors a full circadian system that controls several physiologically relevant functions within this organ. During the last two decades a few laboratories have developed transgenic animal models in which circadian rhythms can be monitored in real time using luciferase activity. The most famous transgenic mouse to record bioluminescence rhythms from different tissues and organs is the PERIOD2::LUCIFERASE (PER2::LUC) mouse developed by the Takahashi laboratory in early 2000. Since then, several studies have used this mouse model to dissect the mammalian circadian system by monitoring the circadian rhythm in the brain, the eye, and in many other peripheral organs and tissues. This chapter describes the methodology to record and analyze bioluminescence rhythms from the retina, retinal pigment epithelium, and cornea of PER2::LUC mice.
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Affiliation(s)
- Kenkichi Baba
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA.
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
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8
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Baba K, Tosini G. Assessing the Role of Melatonin in the Modulation of Visual Functions in the Mouse. Methods Mol Biol 2022; 2550:377-389. [PMID: 36180707 DOI: 10.1007/978-1-0716-2593-4_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The electroretinogram (ERG) is a noninvasive method to evaluate retinal function. It can be applied to patients to be diagnosed a variety of retinal pathologies such as photoreceptor dystrophy, diabetic retinopathy, macular degeneration, and glaucoma. ERG has also been a reliable tool to assess retinal functions in animal studies that range from fish to humans. Melatonin is a neurohormone that regulates several retinal functions within the retina, and previous studies have shown that melatonin plays an important role in the modulation of the ERG in humans and other vertebrates. This chapter describes experimental methods to evaluate retinal function using ERG in the mouse and how to assess the contribution of melatonin. An introduction is provided for materials, environmental settings, recording procedures, and analysis necessary for ERG measurements.
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Affiliation(s)
- Kenkichi Baba
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA.
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
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9
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Tchio C, Musani SK, Quarshie A, Tosini G. Association between MTNR1B polymorphisms and obesity in African American: findings from the Jackson Heart Study. BMC Med Genomics 2021; 14:136. [PMID: 34020621 PMCID: PMC8138980 DOI: 10.1186/s12920-021-00983-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 05/13/2021] [Indexed: 01/02/2023] Open
Abstract
Background Melatonin is a hormone that is secreted at night by the pineal gland. It exerts its function by binding to the MT1 and MT2 receptors, which are encoded by the MTNR1A and MTNR1B genes, respectively. Previous studies reveal that MTNR1B variants are associated with insulin secretion impairments and an increased body mass index (BMI) in individuals of European and Asian ancestries. Obesity is highly prevalent in the US and disproportionately affects African Americans. Here, we hypothesized that common single nucleotide polymorphisms (SNPs) imputed in 1000 Genomes in the MTNR1B gene are associated with adiposity in African American adult men and women and that the association is modified by insomnia. Methods We used an additive genetic model to describe the association between the adiposity traits (BMI and waist circumference) and selected MTNR1B variants in 3,029 Jackson Heart Study participants, with an average age of 55.13 ± 12.84 years, and 62% were women. We regressed the adiposity measures on the estimated allelic or genotypic dosage at every selected SNP and adjusted for age, sex, population stratification, and insomnia. Thirty common SNPs, spanning the MTNR1B gene, with a minor allele frequency ≥ 5%, a call rate ≥ 90%, a Hardy–Weinberg equilibrium p value > 10–6, were available for the analysis. Results The allele T of rs76371840 was associated with adiposity (OR = 1.47 [1.13—1.82]; PFDR-adjusted = 0.0499), and the allele A of rs8192552 showed a significant association with waist circumference (β = 0.023 ± 0.007; PFDR-adjusted = 0.0077) after correcting for multiple testing. When insomnia was included in the adiposity analysis model, the following four variants became significantly associated with adiposity: rs6483208; rs4388843; rs4601728; and rs12804291. Conclusions Our data indicate that polymorphisms in the MTNR1B gene are associated with obesity traits in African Americans. To the best of our knowledge, this is the first study to explore the effect of insomnia on the association between the circadian MTNR1B genetic variants and metabolic traits in an African American sample population. We observed that insomnia affected the association between the MTNR1B variants and adiposity.
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Affiliation(s)
- Cynthia Tchio
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA, 30130, USA.,Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Solomon K Musani
- Jackson Heart Study, University of Mississippi Medical Center, Jackson, MS, USA
| | - Alexander Quarshie
- Clinical Research Center, Morehouse School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA, 30130, USA. .,Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA, USA.
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10
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Tchio C, Baba K, Piccione G, Tosini G. Removal of melatonin receptor type 1 signalling induces dyslipidaemia and hormonal changes in mice subjected to environmental circadian disruption. Endocrinol Diabetes Metab 2021; 4:e00171. [PMID: 33532613 PMCID: PMC7831213 DOI: 10.1002/edm2.171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/02/2020] [Accepted: 07/05/2020] [Indexed: 11/26/2022] Open
Abstract
Background Melatonin is a hormone secreted by the pineal gland in a circadian rhythmic manner with peak synthesis at night. Melatonin signalling was suggested to play a critical role in metabolism during the circadian disruption. Methods Melatonin-proficient (C3H-f+/+ or WT) and melatonin receptor type 1 knockout (MT1 KO) male and female mice were phase-advanced (6 hours) once a week for 6 weeks. Every week, we measured weight, food intake and basal glucose levels. At the end of the experiment, we sacrificed the animals and measured the blood's plasma for lipids profile (total lipids, phospholipids, triglycerides and total cholesterol), metabolic hormones profiles (ghrelin, leptin, insulin, glucagon, glucagon-like-peptide and resistin) and the body composition. Results Environmental circadian disruption (ECD) did not produce any significant effects in C3H-f+/+, while it increased lipids profile in MT1 KO with the significant increase observed in total lipids and triglycerides. For metabolic hormones profile, ECD decreased plasma ghrelin and increased plasma insulin in MT1 KO females. Under control condition, MT1 KO females have significantly different body weight, fat mass, total lipids and total cholesterol than the control C3H-f+/+ females. Conclusion Our data show that melatonin-proficient mice are not affected by ECD. When the MT1 receptors are removed, ECD induced dyslipidaemia in males and females with females experiencing the most adverse effect. Overall, our data demonstrate that MT1 signalling is an essential modulator of lipid and metabolic homeostasis during ECD.
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Affiliation(s)
- Cynthia Tchio
- Circadian Rhythms and Sleep Disorders ProgramNeuroscience InstituteAtlantaGAUSA
- Department of Pharmacology and ToxicologyMorehouse School of MedicineNeuroscience InstituteAtlantaGAUSA
| | - Kenkichi Baba
- Circadian Rhythms and Sleep Disorders ProgramNeuroscience InstituteAtlantaGAUSA
- Department of Pharmacology and ToxicologyMorehouse School of MedicineNeuroscience InstituteAtlantaGAUSA
| | - Giuseppe Piccione
- Dipartimento di Medicine VeterinariaUniversita di MessinaMessinaItaly
| | - Gianluca Tosini
- Circadian Rhythms and Sleep Disorders ProgramNeuroscience InstituteAtlantaGAUSA
- Department of Pharmacology and ToxicologyMorehouse School of MedicineNeuroscience InstituteAtlantaGAUSA
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11
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Goyal V, DeVera C, Baba K, Sellers J, Chrenek MA, Iuvone PM, Tosini G. Photoreceptor Degeneration in Homozygous Male Per2 luc Mice During Aging. J Biol Rhythms 2020; 36:137-145. [PMID: 33135952 DOI: 10.1177/0748730420965285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Per2luc mouse model developed by Takahashi laboratory is one of the most powerful models to study circadian rhythms in real time. In this study, we report that photoreceptors degenerate in male Per2luc mice during aging. Young (2.5- to 5-month-old) and aged (11- to 13.5-month-old) homozygous male Per2luc mice and C57BL/6J mice were used for this study. Retina structure and function were investigated via spectral domain optical coherence tomography (SD-OCT), fundus imaging, and electroretinography (ERG). Zonula occludens-1 (ZO-1) immunofluorescence was used to analyze the retinal pigment epithelium (RPE) morphology. Fundus examination revealed no difference between young Per2luc and wild-type (WT) mice. However, the fundus of aged Per2luc mice showed white deposits, suggestive of age-related drusen-like formation or microglia, which were absent in age-matched WT mice. No differences in retinal structure and function were observed between young Per2luc and WT mice. However, with age, Per2luc mice showed a significant reduction in total retinal thickness with respect to C57BL/6J mice. The reduction was mostly confined to the photoreceptor layer. Consistent with these results, we observed a significant decrease in the amplitude of a- and b-waves of the ERG in aged Per2luc mice. Analysis of the RPE morphology revealed that in aged Per2luc mice there was an increase in compactness and eccentricity with a decrease in solidity with respect to the values observed in WT, pointing toward signs of aging in the RPE of Per2luc mice. Our data demonstrate that homozygous Per2luc mice show photoreceptor degeneration during aging and a premature aging of the RPE.
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Affiliation(s)
- Varunika Goyal
- Neuroscience Institute, Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia
| | - Christopher DeVera
- Neuroscience Institute, Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia
| | - Kenkichi Baba
- Neuroscience Institute, Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia
| | - Jana Sellers
- Department of Ophthalmology, Emory Eye Center, Emory University, Atlanta, Georgia
| | - Micah A Chrenek
- Department of Ophthalmology, Emory Eye Center, Emory University, Atlanta, Georgia
| | - P Michael Iuvone
- Department of Ophthalmology, Emory Eye Center, Emory University, Atlanta, Georgia
| | - Gianluca Tosini
- Neuroscience Institute, Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia.,Department of Ophthalmology, Emory Eye Center, Emory University, Atlanta, Georgia
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12
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Li Y, Ma J, Yao K, Su W, Tan B, Wu X, Huang X, Li T, Yin Y, Tosini G, Yin J. Circadian rhythms and obesity: Timekeeping governs lipid metabolism. J Pineal Res 2020; 69:e12682. [PMID: 32656907 DOI: 10.1111/jpi.12682] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/02/2020] [Accepted: 07/07/2020] [Indexed: 12/29/2022]
Abstract
Almost all living organisms have evolved autoregulatory transcriptional-translational feedback loops that produce oscillations with a period of approximately 24-h. These endogenous time keeping mechanisms are called circadian clocks. The main function of these circadian clocks is to drive overt circadian rhythms in the physiology of the organisms to ensure that main physiological functions are in synchrony with the external environment. Disruption of circadian rhythms caused by genetic or environmental factors has long-term consequences for metabolic health. Of relevance, host circadian rhythmicity and lipid metabolism are increasingly recognized to cross-regulate and the circadian clock-lipid metabolism interplay may involve in the development of obesity. Multiple systemic and molecular mechanisms, such as hormones (ie, melatonin, leptin, and glucocorticoid), the gut microbiome, and energy metabolism, link the circadian clock and lipid metabolism, and predictably, the deregulation of circadian clock-lipid metabolism interplay can increase the risk of obesity, which in turn may exacerbate circadian disorganization. Feeding time and dietary nutrients are two of key environmental Zeitgebers affecting the circadian rhythm-lipid metabolism interplay, and the influencing mechanisms in obesity development are highlighted in this review. Together, the characterization of the clock machinery in lipid metabolism aimed at producing a healthy circadian lifestyle may improve obesity care.
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Affiliation(s)
- Yuying Li
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jie Ma
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Kang Yao
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Wenxuan Su
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bie Tan
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Xin Wu
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Xingguo Huang
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Tiejun Li
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Yulong Yin
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA
| | - Jie Yin
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
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13
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Goyal V, DeVera C, Laurent V, Sellers J, Chrenek MA, Hicks D, Baba K, Iuvone PM, Tosini G. Dopamine 2 Receptor Signaling Controls the Daily Burst in Phagocytic Activity in the Mouse Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2020; 61:10. [PMID: 32396631 PMCID: PMC7405625 DOI: 10.1167/iovs.61.5.10] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Purpose A burst in phagocytosis of spent photoreceptor outer fragments by RPE is a rhythmic process occurring 1 to 2 hours after the onset of light. This phenomenon is considered crucial for the health of the photoreceptors and RPE. We have recently reported that dopamine, via dopamine 2 receptor (D2R), shifts the circadian rhythm in the RPE. Methods Here, we first investigated the impact of the removal of D2R on the daily peak of phagocytosis by RPE and then we analyzed the function and morphology of retina and RPE in the absence of D2R. Results D2R knockout (KO) mice do not show a daily burst of phagocytic activity after the onset of light. RNA sequencing revealed a total of 394 differentially expressed genes (DEGs) between ZT 23 and ZT 1 in the control mice, whereas in D2R KO mice, we detected 1054 DEGs. Pathway analysis of the gene expression data implicated integrin signaling to be one of the upregulated pathways in control but not in D2R KO mice. Consistent with the gene expression data, phosphorylation of focal adhesion kinase (FAK) did not increase significantly in KO mice at ZT 1. No difference in retinal thickness, visual function, or morphology of RPE cells was observed between wild-type (WT) and D2R KO mice at the age of 3 and 12 months. Conclusions Our data suggest that removal of D2R prevents the burst of phagocytosis and a related increase in the phosphorylation of FAK after light onset. The pathway analysis points toward a putative role of D2R in controlling integrin signaling, which is known to play an important role in the control of the daily burst of phagocytosis by the RPE. Our data also indicate that the absence of the burst of phagocytic activity in the early morning does not produce any apparent deleterious effect on the retina or RPE up to 1 year of age.
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14
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DeVera C, Tosini G. Circadian analysis of the mouse retinal pigment epithelium transcriptome. Exp Eye Res 2020; 193:107988. [PMID: 32105725 DOI: 10.1016/j.exer.2020.107988] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/21/2020] [Accepted: 02/21/2020] [Indexed: 01/01/2023]
Abstract
The presence of a phagocytic peak of photoreceptor outer segments by the retinal pigment epithelium (RPE) one or 2 h after the onset of light has been reported for several diurnal and nocturnal species. This peak in phagocytic activity also persists under constant lighting conditions (i.e., constant light or dark) thus demonstrating that the timing of this peak is driven by a circadian clock. The aim of this study was to investigate the change in RPE whole transcriptome at two different circadian times (CT; 1 h before (CT23) and 1 h after (CT1) subjective light onset). C57BL/6J male mice were maintained in constant dark conditions for three days and euthanized under red light (<1 lux) at CT23 and CT1. RPE was isolated from whole eyes for RNA library preparation and sequencing on an Illumina HiSeq4000 platform. 14,083 mouse RPE transcripts were detected in common between CT23 and CT1. 12,005 were protein coding transcripts and 2078 were non-protein coding transcripts. 2421 protein coding transcripts were significantly upregulated whereas only 3 transcripts were significantly downregulated and 12 non-protein coding transcripts were significantly upregulated and 31 non-protein coding transcripts were significantly downregulated at CT1 when compared to CT23 (p < 0.05, fold change ≥ ±2.0). Of the protein coding transcripts, most of them were characterized as: enzymes, kinases, and transcriptional regulators with a large majority of activity in the cytoplasm, nucleus, and plasma membrane. Non-protein coding transcripts included biotypes such as long-non coding RNAs and pseudogenes. Gene ontology analysis and ingenuity pathway analysis revealed that differentially expressed transcripts were associated with integrin signaling, oxidative phosphorylation, protein phosphorylation, and actin cytoskeleton remodeling suggesting that these previously identified phagocytic pathways are under circadian control. Our analysis identified new pathways (e.g., increased mitochondrial respiration via increased oxidative phosphorylation) that may be involved in the circadian control of phagocytic activity. In addition, our dataset suggests a possible regulatory role for the identified non-protein coding transcripts in mediating the complex function of RPE phagocytosis. Finally, our results also indicate, as seen in other tissues, about 20% of the whole RPE transcriptome may be under circadian clock regulation.
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Affiliation(s)
- Christopher DeVera
- Department of Pharmacology and Toxicology, Atlanta, GA, USA, 30310; Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA, 30310
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology, Atlanta, GA, USA, 30310; Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA, 30310.
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15
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Sánchez-Bretaño A, Suen TC, Baba K, DeBruyne J, Tosini G. Melatonin receptor heterodimerization in a photoreceptor-like cell line endogenously expressing melatonin receptors. Mol Vis 2019; 25:791-799. [PMID: 31819341 PMCID: PMC6887793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 11/29/2019] [Indexed: 11/09/2022] Open
Abstract
Purpose Melatonin signaling plays an important role in the modulation of retinal physiology and photoreceptor viability during aging. In this study, we investigated whether 661W cells-a photoreceptor-like cell that endogenously expresses melatonin receptor type 1 (MT1) and melatonin receptor type 2 (MT2) receptors-represent a useful model for studying the biology of heterodimerization and signaling of MT1/2 receptors. Methods 661W cells were cultured, and MT1/MT2 heterodimerization in 661W cells was assessed with proximity ligation assay. MT2 was removed from the 661W cells using the MT2-CRISPR/Cas9 system. Melatonin receptor signaling was investigated by measuring cAMP levels and activation of the AKT-FoxO1 pathway. Results The results demonstrated that heterodimerization of MT1 and MT2 receptors occurs in 661W cells. The pathways activated by MT1/MT2 heterodimer (MT1/2h) in 661W cells are similar to those previously reported in mouse photoreceptors. Disruption of the heterodimer formation by genetically ablating MT2 from 661W cells abolished the activation of melatonin signaling in these cells. Conclusions The data indicated that in 661W cells, MT1 and MT2 receptors are functional only when they are associated in a heteromeric complex, as occurs in mouse photoreceptors. 661W cells represent a useful model for studying the mechanism underlying MT1/MT2 heterodimerization.
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16
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Cardinali DP, Delagrange P, Dubocovich ML, Jockers R, Krause DN, Markus RP, Olcese J, Pintor J, Renault N, Sugden D, Tosini G, Zlotos DP. Melatonin receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database. ACTA ACUST UNITED AC 2019. [DOI: 10.2218/gtopdb/f39/2019.4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Melatonin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Melatonin Receptors [36]) are activated by the endogenous ligands melatonin and clinically used drugs like ramelteon, agomelatine and tasimelteon.
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17
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Buonfiglio D, Tchio C, Furigo I, Donato J, Baba K, Cipolla-Neto J, Tosini G. Removing melatonin receptor type 1 signaling leads to selective leptin resistance in the arcuate nucleus. J Pineal Res 2019; 67:e12580. [PMID: 30968433 PMCID: PMC6687516 DOI: 10.1111/jpi.12580] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 03/28/2019] [Accepted: 04/04/2019] [Indexed: 12/15/2022]
Abstract
Recent studies have highlighted the involvement of melatonin in the regulation of energy homeostasis. In this study, we report that mice lacking melatonin receptor 1 (MT1 KO) gained more weight, had a higher cumulative food intake, and were more hyperphagic after fasting compared to controls (WT). In response to a leptin injection, MT1 KO mice showed a diminished reduction in body weight and food intake. To evaluate hypothalamic leptin signaling, we tested leptin-induced phosphorylation of the signal transducer and activator of transcription 3 (STAT3). Leptin failed to induce STAT3 phosphorylation in MT1 KO mice beyond levels observed in mice injected with phosphate-buffered saline (PBS). Furthermore, STAT3 phosphorylation within the arcuate nucleus (ARH) was decreased in MT1 KO mice. Leptin receptor mRNA levels in the hypothalamus of MT1 KO were significantly reduced (about 50%) compared to WT. This study shows that: (a) MT1 deficiency causes weight gain and increased food intake; (b) a lack of MT1 signaling induces leptin resistance; (c) leptin resistance is ARH region-specific; and (d) leptin resistance is likely due to down-regulation of the leptin receptor. Our data demonstrate that MT1 signaling is an important modulator of leptin signaling.
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Affiliation(s)
- Daniella Buonfiglio
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, Brazil
- Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Cynthia Tchio
- Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Isadora Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, Brazil
| | - José Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, Brazil
| | - Kenkichi Baba
- Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - José Cipolla-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, Brazil
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
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18
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DeVera C, Baba K, Tosini G. Retinal Circadian Clocks are Major Players in the Modulation of Retinal Functions and Photoreceptor Viability. Yale J Biol Med 2019; 92:233-240. [PMID: 31249484 PMCID: PMC6585523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Circadian rhythms control many biochemical and physiological functions within the body of an organism. These circadian rhythms are generated by a molecular clock that is located in almost every cell of the body. Accumulating data indicate that dysfunction of the circadian clock negatively affects the health status of the tissue in which the circadian clock has been disabled. The eye also contains a complex circadian system that regulates many important functions such as the processing of light information, the release of neurotransmitters, and phagocytic activity by the retinal pigment epithelium, to name just a few. Emerging experimental evidence indicates that dysfunction of the circadian clock within the retina has severe consequence for retinal function and photoreceptor viability. The aim of this review is to provide the reader with a summary of current knowledge about the eye circadian system and what effects emerge with a disruption of this system.
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Affiliation(s)
| | | | - Gianluca Tosini
- To whom all correspondence should be addressed: Gianluca Tosini, PhD, Mailing address: 720 Westview Dr. SW, Atlanta, GA, 30310-1495; Tel: 404-756-5214, Fax: 404-752-1041,
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19
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Felder-Schmittbuhl MP, Buhr ED, Dkhissi-Benyahya O, Hicks D, Peirson SN, Ribelayga CP, Sandu C, Spessert R, Tosini G. Ocular Clocks: Adapting Mechanisms for Eye Functions and Health. Invest Ophthalmol Vis Sci 2019; 59:4856-4870. [PMID: 30347082 PMCID: PMC6181243 DOI: 10.1167/iovs.18-24957] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vision is a highly rhythmic function adapted to the extensive changes in light intensity occurring over the 24-hour day. This adaptation relies on rhythms in cellular and molecular processes, which are orchestrated by a network of circadian clocks located within the retina and in the eye, synchronized to the day/night cycle and which, together, fine-tune detection and processing of light information over the 24-hour period and ensure retinal homeostasis. Systematic or high throughput studies revealed a series of genes rhythmically expressed in the retina, pointing at specific functions or pathways under circadian control. Conversely, knockout studies demonstrated that the circadian clock regulates retinal processing of light information. In addition, recent data revealed that it also plays a role in development as well as in aging of the retina. Regarding synchronization by the light/dark cycle, the retina displays the unique property of bringing together light sensitivity, clock machinery, and a wide range of rhythmic outputs. Melatonin and dopamine play a particular role in this system, being both outputs and inputs for clocks. The retinal cellular complexity suggests that mechanisms of regulation by light are diverse and intricate. In the context of the whole eye, the retina looks like a major determinant of phase resetting for other tissues such as the retinal pigmented epithelium or cornea. Understanding the pathways linking the cell-specific molecular machineries to their cognate outputs will be one of the major challenges for the future.
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Affiliation(s)
- Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Ethan D Buhr
- Department of Ophthalmology, University of Washington Medical School, Seattle, Washington, United States
| | - Ouria Dkhissi-Benyahya
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - David Hicks
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, United States
| | - Cristina Sandu
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Strasbourg, France
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
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20
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Tchio Mantho CI, Musani S, Quarshie A, Tosini G. SAT-107 The Association between MTNR1B Polymorphisms and Obesity in an African American Population: Findings from the Jackson Heart Study. J Endocr Soc 2019. [PMCID: PMC6552455 DOI: 10.1210/js.2019-sat-107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Obesity is a growing pandemic that affects 36.5% of US adults, and it is prevalent across different ethnic groups, with Non-Hispanic blacks having the highest age adjusted rates. Obesity presents a complex etiology which arises from the interaction of both genetic and environmental factors. Recent genome-wide association studies have demonstrated that polymorphisms in the gene encoding the human melatonin receptor type 2 MTNR1B are linked to an increased in metabolic traits (fasting glucose, BMI, and HOMA-IR), and thus to the risk of developing type 2 diabetes (T2D) in Caucasian and Han population. The aim of this present study was to investigate whether variations in MTNR1B in an African American population (Jackson Heart Study, JHS) were associated with obesity and T2D traits. To that aim, we analyzed all JHS participants (n=3020) with 1000G imputed genotypes for our gene of interest. We analyzed common variants (MAF ≥ 5%) with a high imputation quality of >80% within the MTNR1B gene for their association with body mass index (BMI) (>30), waist circumference (women >88 cm and men >102cm), LDL (>130mg/dL), HDL (<60mg/dL), total cholesterol (>200mg/dL), HOMA-IR (>2.0), HbA1C (>5.6%), and fasting glucose (>126 mg/dL). We identified 16 common variants which are significantly associated with BMI, waist, and HOMA-IR. In conclusion, our data indicate that polymorphisms in MTNR1B may be associated with obesity traits and insulin resistance in an African American population.
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Affiliation(s)
| | - Solomon Musani
- Jackson Heart Study University of Mississippi Medical Center, Jackson, MS, United States
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21
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Jilg A, Bechstein P, Saade A, Dick M, Li TX, Tosini G, Rami A, Zemmar A, Stehle JH. Melatonin modulates daytime-dependent synaptic plasticity and learning efficiency. J Pineal Res 2019; 66:e12553. [PMID: 30618149 PMCID: PMC6405292 DOI: 10.1111/jpi.12553] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/27/2018] [Accepted: 12/25/2018] [Indexed: 12/15/2022]
Abstract
Mechanisms of hippocampus-related memory formation are time-of-day-dependent. While the circadian system and clock genes are related to timing of hippocampal mnemonic processes (acquisition, consolidation, and retrieval of long-term memory [LTM]) and long-term potentiation (LTP), little is known about temporal gating mechanisms. Here, the role of the neurohormone melatonin as a circadian time cue for hippocampal signaling and memory formation was investigated in C3H/He wildtype (WT) and melatonin receptor-knockout ( MT 1 / 2 - / - ) mice. Immunohistochemical and immunoblot analyses revealed the presence of melatonin receptors on mouse hippocampal neurons. Temporal patterns of time-of-day-dependent clock gene protein levels were profoundly altered in MT 1 / 2 - / - mice compared to WT animals. On the behavioral level, WT mice displayed better spatial learning efficiency during daytime as compared to nighttime. In contrast, high error scores were observed in MT 1 / 2 - / - mice during both, daytime and nighttime acquisition. Day-night difference in LTP, as observed in WT mice, was absent in MT 1 / 2 - / - mice and in WT animals, in which the sympathetic innervation of the pineal gland was surgically removed to erase rhythmic melatonin synthesis. In addition, treatment of melatonin-deficient C57BL/6 mice with melatonin at nighttime significantly improved their working memory performance at daytime. These results illustrate that melatonin shapes time-of-day-dependent learning efficiency in parallel to consolidating expression patterns of clock genes in the mouse hippocampus. Our data suggest that melatonin imprints a time cue on mouse hippocampal signaling and gene expression to foster better learning during daytime.
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Affiliation(s)
- Antje Jilg
- Juha Hernesniemi International Neurosurgery Center, Henan Provincial People’s Hospital, School of Medicine, Henan University, Zhengzhou 450003, China
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
| | - Philipp Bechstein
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
| | - Anastasia Saade
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
| | - Moritz Dick
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
| | - Tian Xiao Li
- Juha Hernesniemi International Neurosurgery Center, Henan Provincial People’s Hospital, School of Medicine, Henan University, Zhengzhou 450003, China
| | - Gianluca Tosini
- Morehouse School of Medicine, Pharmacology & Toxicology, 720 Westview Drive SW, Atlanta, GA 30310-1495, USA
| | - Abdelhaq Rami
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
| | - Ajmal Zemmar
- Juha Hernesniemi International Neurosurgery Center, Henan Provincial People’s Hospital, School of Medicine, Henan University, Zhengzhou 450003, China
- Brain Research Institute, University of Zurich, 8057 Zurich, Switzerland
- Department of Biology and Department of Health Sciences and Technology, ETH Zurich, CH-8057 Zurich, Switzerland
| | - Jörg H. Stehle
- Juha Hernesniemi International Neurosurgery Center, Henan Provincial People’s Hospital, School of Medicine, Henan University, Zhengzhou 450003, China
- Institute of Cellular and Molecular Anatomy, Goethe-University Frankfurt, Germany
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22
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Owino S, Buonfiglio DDC, Tchio C, Tosini G. Melatonin Signaling a Key Regulator of Glucose Homeostasis and Energy Metabolism. Front Endocrinol (Lausanne) 2019; 10:488. [PMID: 31379753 PMCID: PMC6651071 DOI: 10.3389/fendo.2019.00488] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/04/2019] [Indexed: 12/29/2022] Open
Abstract
Melatonin, a hormone synthesized by both the pineal gland and retina, functions as an important modulator of a number of physiological functions. In addition to its rather well-established roles in the regulation of circadian rhythms, sleep, and reproduction, melatonin has also been identified as an important regulator of glucose metabolism. Recent genomic studies have also shown that disruption of melatonin receptors signaling may contribute to the pathogenesis of type 2 diabetes, although the exact mechanisms underlying its action remain unclear. Additionally, a large number of animal studies have highlighted a role for melatonin in the regulation of both glucose metabolism and energy balance. This review summarizes the current knowledge on the role that melatonin and its associated receptors play in the regulation of metabolism.
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Affiliation(s)
- Sharon Owino
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, United States
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, United States
| | - Daniella D. C. Buonfiglio
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, United States
- Department of Physiology and Biophysics, Institute of Biomedical Sciences-I, University of São Paulo (USP), São Paulo, Brazil
| | - Cynthia Tchio
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, United States
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, United States
- *Correspondence: Gianluca Tosini
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23
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Baba K, Piano I, Lyuboslavsky P, Chrenek MA, Sellers JT, Zhang S, Gargini C, He L, Tosini G, Iuvone PM. Removal of clock gene Bmal1 from the retina affects retinal development and accelerates cone photoreceptor degeneration during aging. Proc Natl Acad Sci U S A 2018; 115:13099-13104. [PMID: 30498030 PMCID: PMC6305005 DOI: 10.1073/pnas.1808137115] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The mammalian retina contains an autonomous circadian clock system that controls many physiological functions within this tissue. Previous studies on young mice have reported that removal of the key circadian clock gene Bmal1 from the retina affects the circadian regulation of visual function, but does not affect photoreceptor viability. Because dysfunction in the circadian system is known to affect cell viability during aging in other systems, we compared the effect of Bmal1 removal from the retina on visual function, inner retinal structure, and photoreceptor viability in young (1 to 3 months) and aged (24 to 26 months) mice. We found that removal of Bmal1 from the retina significantly affects visual information processing in both rod and cone pathways, reduces the thickness of inner retinal nuclear and plexiform layers, accelerates the decline of visual functions during aging, and reduces the viability of cone photoreceptors. Our results thus suggest that circadian clock dysfunction, caused by genetic or other means, may contribute to the decline of visual function during development and aging.
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Affiliation(s)
- Kenkichi Baba
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA 30310-1495
| | - Ilaria Piano
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA 30310-1495
- Department of Pharmacy, University of Pisa, Pisa 56121, Italy
| | - Polina Lyuboslavsky
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
| | - Micah A Chrenek
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
| | - Jana T Sellers
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
| | - Shuo Zhang
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
- Institute of Ophthalmology, Central South University, Changsha, Hunan 410008, China
| | - Claudia Gargini
- Department of Pharmacy, University of Pisa, Pisa 56121, Italy
| | - Li He
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Gianluca Tosini
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA 30310-1495;
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013
| | - P Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322-1013;
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
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24
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Abstract
The eye contains a circadian system that acts independently from the master circadian clock located in the brain. This circadian system regulates important physiological functions within the eye. Emerging experimental evidence also indicates that disruption of the ocular circadian clock, or its outputs, negatively affects the overall health of the eye. Although previous studies have investigated the effect of aging on the regulation of circadian rhythms, no study has investigated the effects of aging on the circadian rhythm in the ocular system. The aim of the present study was to investigate how aging affects the circadian rhythm of PER2::LUC bioluminescence in the retina, retinal pigment epithelium (RPE), and cornea. Our data suggest that among the 3 different ocular tissues investigated, the retina appears to be the most affected by aging whereas the RPE and cornea are less affected by aging. Our data, along with studies of other organs and tissues, suggest that reduction in the amplitude of rhythms is probably the most severe effect of aging on the circadian clock.
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Affiliation(s)
| | - Gianluca Tosini
- Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia
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25
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Owino S, Sánchez-Bretaño A, Tchio C, Cecon E, Karamitri A, Dam J, Jockers R, Piccione G, Noh HL, Kim T, Kim JK, Baba K, Tosini G. Nocturnal activation of melatonin receptor type 1 signaling modulates diurnal insulin sensitivity via regulation of PI3K activity. J Pineal Res 2018; 64:10.1111/jpi.12462. [PMID: 29247541 PMCID: PMC5843510 DOI: 10.1111/jpi.12462] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/27/2017] [Indexed: 12/26/2022]
Abstract
Recent genetic studies have highlighted the potential involvement of melatonin receptor 1 (MT1 ) and melatonin receptor 2 (MT2 ) in the pathogenesis of type 2 diabetes. Here, we report that mice lacking MT1 (MT1 KO) tend to accumulate more fat mass than WT mice and exhibit marked systemic insulin resistance. Additional experiments revealed that the main insulin signaling pathway affected by the loss of MT1 was the activation of phosphatidylinositol-3-kinase (PI3K). Transcripts of both catalytic and regulatory subunits of PI3K were strongly downregulated within MT1 KO mice. Moreover, the suppression of nocturnal melatonin levels within WT mice, by exposing mice to constant light, resulted in impaired PI3K activity and insulin resistance during the day, similar to what was observed in MT1 KO mice. Inversely, administration of melatonin to WT mice exposed to constant light was sufficient and necessary to restore insulin-mediated PI3K activity and insulin sensitivity. Hence, our data demonstrate that the activation of MT1 signaling at night modulates insulin sensitivity during the day via the regulation of the PI3K transcription and activity. Lastly, we provide evidence that decreased expression of MTNR1A (MT1 ) in the liver of diabetic individuals is associated with poorly controlled diabetes.
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Affiliation(s)
- Sharon Owino
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Aida Sánchez-Bretaño
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Cynthia Tchio
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Erika Cecon
- Inserm, U1016, Institut Cochin, Paris, France
| | | | - Julie Dam
- Inserm, U1016, Institut Cochin, Paris, France
| | | | | | - Hye Lim Noh
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Taekyoon Kim
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Jason K. Kim
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
- Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, University of Massachusetts Medical School, Worcester, MA
| | - Kenkichi Baba
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
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26
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Abstract
Circadian rhythms are present in most living organisms, and these rhythms are not just a consequence of the day/night fluctuation, but rather they are generated by endogenous biological clocks with a periodicity of about 24 h. In mammals, the master pacemaker of circadian rhythms is localized in the suprachiasmatic nuclei (SCN) of the hypothalamus. The SCN controls circadian rhythms in peripheral organs. The retina also contains circadian clocks which regulate many aspects of retinal physiology, independently of the SCN. Emerging experimental evidence indicates that the retinal circadian clocks also affect ocular health, and a few studies have now demonstrated that disruption of retinal clocks may contribute to the development of retinal diseases. Our study indicates that in mice lacking the clock gene Bmal1, photoreceptor viability during aging is significantly reduced. Bmal1 knockout mice at 8-9 months of age have 20-30% less nuclei in the outer nuclear layer. No differences were observed in the other retinal layers. Our study suggests that the retinal circadian clock is an important modulator of photoreceptor health.
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Affiliation(s)
- Kenkichi Baba
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, USA.
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - P Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology Morehouse School of Medicine, Neuroscience Institute, Atlanta, GA, USA
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27
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Sánchez-Bretaño A, Baba K, Janjua U, Piano I, Gargini C, Tosini G. Melatonin partially protects 661W cells from H 2O 2-induced death by inhibiting Fas/FasL-caspase-3. Mol Vis 2017; 23:844-852. [PMID: 29259391 PMCID: PMC5723148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/01/2017] [Indexed: 11/30/2022] Open
Abstract
PURPOSE Previous studies have shown that melatonin (MEL) signaling is involved in the modulation of photoreceptor viability during aging. Recent work by our laboratory suggested that MEL may protect cones by modulating the Fas/FasL-caspase-3 pathway. In this study, we first investigated the presence of MEL receptors (MT1 and MT2) in 661W cells, then whether MEL can prevent H2O2-induced cell death, and last, through which pathway MEL confers protection. METHODS The mRNA and proteins of the MEL receptors were detected with quantitative PCR (q-PCR) and immunocytochemistry, respectively. To test the protective effect of MEL, 661W cells were treated with H2O2 for 2 h in the presence or absence of MEL, a MEL agonist, and an antagonist. To study the pathways involved in H2O2-mediated cell death, a Fas/FasL antagonist was used before the exposure to H2O2. Finally, Fas/FasL and caspase-3 mRNA was analyzed with q-PCR and immunocytochemistry in cells treated with H2O2 and/or MEL. Cell viability was analyzed by using Trypan Blue. RESULTS Both MEL receptors (MT1 and MT2) were detected at the mRNA and protein levels in 661W cells. MEL partially prevented H2O2-mediated cell death (20-25%). This effect was replicated with IIK7 (a melatonin receptor agonist) when used at a concentration of 1 µM. Preincubation with luzindole (a melatonin receptor antagonist) blocked MEL protection. Kp7-6, an antagonist of Fas/FasL, blocked cell death caused by H2O2 similarly to what was observed for MEL. Fas, FasL, and caspase-3 expression was increased in cells treated with H2O2, and this effect was prevented by MEL. Finally, MEL treatment partially prevented the activation of caspase-3 caused by H2O2. CONCLUSIONS The results demonstrate that MEL receptors are present and functional in 661W cells. MEL can prevent photoreceptor cell death induced by H2O2 via the inhibition of the proapoptotic pathway Fas/FasL-caspase-3.
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Affiliation(s)
- Aída Sánchez-Bretaño
- Department of Pharmacology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA
| | - Kenkichi Baba
- Department of Pharmacology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA
| | - Uzair Janjua
- Department of Pharmacology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA
| | - Ilaria Piano
- Department of Pharmacology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA,Dipartimento di Farmacia, Universita di Pisa, Pisa, Italy
| | | | - Gianluca Tosini
- Department of Pharmacology and Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA
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28
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Laurent V, Sengupta A, Sánchez-Bretaño A, Hicks D, Tosini G. Melatonin signaling affects the timing in the daily rhythm of phagocytic activity by the retinal pigment epithelium. Exp Eye Res 2017; 165:90-95. [PMID: 28941766 DOI: 10.1016/j.exer.2017.09.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/07/2017] [Accepted: 09/17/2017] [Indexed: 11/30/2022]
Abstract
Earlier studies in Xenopus have indicated a role for melatonin in the regulation of retinal disk shedding, but the role of melatonin in the regulation of daily rhythm in mammalian disk shedding and phagocytosis is still unclear. We recently produced a series of transgenic mice lacking melatonin receptor type 1 (MT1) or type 2 (MT2) in a melatonin-proficient background and have shown that removal of MT1 and MT2 receptors induces significant effects on daily and circadian regulation of the electroretinogram as well as on the viability of photoreceptor cells during aging. In this study we investigated the daily rhythm of phagocytic activity by the retinal pigment epithelium in MT1 and MT2 knock-out mice. Our data indicate that in MT1 and MT2 knock-out mice the peak of phagocytosis is advanced by 3 h with respect to wild-type mice and occurred in dark rather than after the onset of light, albeit the mean phagocytic activity over the 24-h period did not change among the three genotypes. Nevertheless, this small change in the profile of daily phagocytic rhythms may produce a significant effect on retinal health since MT1 and MT2 knock-out mice showed a significant increase in lipofuscin accumulation in the retinal pigment epithelium.
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Affiliation(s)
- Virgine Laurent
- Institut des Neurosciences Cellulaires et Intégratives (INCI), CNRS UPR3212, 5 rue Blaise Pascal, 67084 Strasbourg, France
| | - Anamika Sengupta
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, USA
| | - Aída Sánchez-Bretaño
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, USA
| | - David Hicks
- Institut des Neurosciences Cellulaires et Intégratives (INCI), CNRS UPR3212, 5 rue Blaise Pascal, 67084 Strasbourg, France
| | - Gianluca Tosini
- Neuroscience Institute, Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, USA.
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29
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Vancura P, Wolloscheck T, Baba K, Tosini G, Iuvone PM, Spessert R. Circadian and Dopaminergic Regulation of Fatty Acid Oxidation Pathway Genes in Retina and Photoreceptor Cells. PLoS One 2016; 11:e0164665. [PMID: 27727308 PMCID: PMC5058478 DOI: 10.1371/journal.pone.0164665] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 09/28/2016] [Indexed: 12/17/2022] Open
Abstract
The energy metabolism of the retina might comply with daily changes in energy demand and is impaired in diabetic retinopathy-one of the most common causes of blindness in Europe and the USA. The aim of this study was to investigate putative adaptation of energy metabolism in healthy and diabetic retina. Hence expression analysis of metabolic pathway genes was performed using quantitative polymerase chain reaction, semi-quantitative western blot and immunohistochemistry. Transcriptional profiling of key enzymes of energy metabolism identified transcripts of mitochondrial fatty acid β-oxidation enzymes, i.e. carnitine palmitoyltransferase-1α (Cpt-1α) and medium chain acyl-CoA dehydrogenase (Acadm) to display daily rhythms with peak values during daytime in preparations of the whole retina and microdissected photoreceptors. The cycling of both enzymes persisted in constant darkness, was dampened in mice deficient for dopamine D4 (D4) receptors and was altered in db/db mice-a model of diabetic retinopathy. The data of the present study are consistent with circadian clock-dependent and dopaminergic regulation of fatty acid oxidation in retina and its putative disturbance in diabetic retina.
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MESH Headings
- Acyl-CoA Dehydrogenase/genetics
- Acyl-CoA Dehydrogenase/metabolism
- Animals
- Carnitine O-Palmitoyltransferase/genetics
- Carnitine O-Palmitoyltransferase/metabolism
- Circadian Rhythm/physiology
- Diabetic Retinopathy/metabolism
- Diabetic Retinopathy/pathology
- Disease Models, Animal
- Dopamine/metabolism
- Energy Metabolism
- Fatty Acids/chemistry
- Fatty Acids/metabolism
- Female
- Male
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Obese
- Microscopy, Fluorescence
- Oxidation-Reduction
- Photoreceptor Cells/metabolism
- Receptor, Melatonin, MT1/deficiency
- Receptor, Melatonin, MT1/genetics
- Receptors, Dopamine D4/deficiency
- Receptors, Dopamine D4/genetics
- Retina/metabolism
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Affiliation(s)
- Patrick Vancura
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Tanja Wolloscheck
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Kenkichi Baba
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - P. Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
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30
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Jockers R, Delagrange P, Dubocovich ML, Markus RP, Renault N, Tosini G, Cecon E, Zlotos DP. Update on melatonin receptors: IUPHAR Review 20. Br J Pharmacol 2016; 173:2702-25. [PMID: 27314810 DOI: 10.1111/bph.13536] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/15/2016] [Accepted: 05/19/2016] [Indexed: 02/06/2023] Open
Abstract
Melatonin receptors are seven transmembrane-spanning proteins belonging to the GPCR superfamily. In mammals, two melatonin receptor subtypes exist - MT1 and MT2 - encoded by the MTNR1A and MTNR1B genes respectively. The current review provides an update on melatonin receptors by the corresponding subcommittee of the International Union of Basic and Clinical Pharmacology. We will highlight recent developments of melatonin receptor ligands, including radioligands, and give an update on the latest phenotyping results of melatonin receptor knockout mice. The current status and perspectives of the structure of melatonin receptor will be summarized. The physiological importance of melatonin receptor dimers and biologically important and type 2 diabetes-associated genetic variants of melatonin receptors will be discussed. The role of melatonin receptors in physiology and disease will be further exemplified by their functions in the immune system and the CNS. Finally, antioxidant and free radical scavenger properties of melatonin and its relation to melatonin receptors will be critically addressed.
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Affiliation(s)
- Ralf Jockers
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Paris, France
| | | | - Margarita L Dubocovich
- Department Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Science, University at Buffalo (SUNY), Buffalo, USA
| | - Regina P Markus
- Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | | | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Erika Cecon
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Paris, France
| | - Darius P Zlotos
- Department of Pharmaceutical Chemistry, The German University in Cairo, New Cairo City, Cairo, Egypt
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31
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Abstract
Purpose Previous studies have demonstrated that melatonin has an important role in the modulation of photoreceptor viability during aging and may be involved in the pathogenesis of age-related macular degeneration.This hormone exerts its influence by binding to G-protein coupled receptors named melatonin receptor 1 (MT1) and 2 (MT2). Melatonin receptors 1 and 2 activate a wide variety of signaling pathways. Methods Melatonin-proficient mice (C3H/f+/+) and melatonin-proficient mice lacking MT1 or MT2 receptors (MT1−/− and MT2−/−) were used in this study. Mice were killed at the ages of 3 and 18 months, and photoreceptor viability was determined by counting nuclei number in the outer nuclear layer (ONL). Cones were identified by immunohistochemistry using peanut agglutinin (PNA) and green/red and blue opsin antibodies. Protein kinase B (AKT) and forkhead box O (FOXO1) were assessed by Western blotting and immunohistochemistry. Results The number of nuclei in the ONL was significantly reduced in C3Hf+/+, MT1−/−, and MT2−/− mice at 18 months of age with respect to 3-month-old animals. In 18-month-old MT1−/− and MT2−/− mice, but not in C3H/f+/+, the number of cones was significantly reduced with respect to young MT1−/− and MT2−/− mice or age-matched C3H/f+/+. In C3H/f+/+, activation of the AKT-FOXO1 pathway in the photoreceptors showed a significant difference between night and day. Conclusions Our data indicate that disruption of MT1/MT2 heteromer signaling induces a reduction in the number of photoreceptors during aging and also suggest that the AKT-FOXO1 survival pathway may be involved in the mechanism by which melatonin protects photoreceptors.
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Affiliation(s)
- Coralie Gianesini
- Department of Pharmacology and Toxicology and Neuroscience Institute Morehouse School of Medicine, Atlanta, Georgia, United States 2Centre National de la Recherche Scientifique Unités Propres de Recherche 3212, Institute for Cellular and Integrative Neuro
| | - Susumu Hiragaki
- Department of Pharmacology and Toxicology and Neuroscience Institute Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Virginie Laurent
- Centre National de la Recherche Scientifique Unités Propres de Recherche 3212, Institute for Cellular and Integrative Neurosciences, Strasbourg, France
| | - David Hicks
- Centre National de la Recherche Scientifique Unités Propres de Recherche 3212, Institute for Cellular and Integrative Neurosciences, Strasbourg, France
| | - Gianluca Tosini
- Department of Pharmacology and Toxicology and Neuroscience Institute Morehouse School of Medicine, Atlanta, Georgia, United States
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32
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Owino S, Contreras-Alcantara S, Baba K, Tosini G. Melatonin Signaling Controls the Daily Rhythm in Blood Glucose Levels Independent of Peripheral Clocks. PLoS One 2016; 11:e0148214. [PMID: 26824606 PMCID: PMC4732609 DOI: 10.1371/journal.pone.0148214] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/14/2016] [Indexed: 01/01/2023] Open
Abstract
Melatonin is rhythmically secreted by both the pineal gland and retina in a circadian fashion, with its peak synthesis occurring during the night. Once synthesized, melatonin exerts its effects by binding to two specific G-protein coupled receptors-melatonin receptor type 1(MT1) and melatonin receptor type 2(MT2). Recent studies suggest the involvement of MT1 and MT2 in the regulation of glucose homeostasis; however the ability of melatonin signaling to impart timing cues on glucose metabolism remains poorly understood. Here we report that the removal of MT1 or MT2 in mice abolishes the daily rhythm in blood glucose levels. Interestingly, removal of melatonin receptors produced small effects on the rhythmic expression patterns of clock genes within skeletal muscle, liver, and adipose tissue. Taken together, our data suggest that the loss of the daily rhythm in blood glucose observed in MT1(-/-) and MT2(-/-) mice does not occur as a consequence of 'disrupted' clocks within insulin sensitive tissues. Finally our results highlight a diurnal contribution of melatonin receptor signaling in the daily regulation of blood glucose levels.
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MESH Headings
- Adipose Tissue/metabolism
- Animals
- Blood Glucose/metabolism
- CLOCK Proteins/genetics
- CLOCK Proteins/metabolism
- Circadian Rhythm/genetics
- Gene Expression Regulation
- Homeostasis
- Liver/metabolism
- Male
- Melatonin/metabolism
- Mice
- Mice, Knockout
- Muscle, Skeletal/metabolism
- Pineal Gland/metabolism
- Receptor, Melatonin, MT1/deficiency
- Receptor, Melatonin, MT1/genetics
- Receptor, Melatonin, MT2/deficiency
- Receptor, Melatonin, MT2/genetics
- Retina/metabolism
- Signal Transduction
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Affiliation(s)
- Sharon Owino
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Susana Contreras-Alcantara
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Kenkichi Baba
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
- * E-mail: (KB); (GT)
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
- * E-mail: (KB); (GT)
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33
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Kunst S, Wolloscheck T, Kelleher DK, Wolfrum U, Sargsyan SA, Iuvone PM, Baba K, Tosini G, Spessert R. Pgc-1α and Nr4a1 Are Target Genes of Circadian Melatonin and Dopamine Release in Murine Retina. Invest Ophthalmol Vis Sci 2016; 56:6084-94. [PMID: 26393668 DOI: 10.1167/iovs.15-17503] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
PURPOSE The neurohormones melatonin and dopamine mediate clock-dependent/circadian regulation of inner retinal neurons and photoreceptor cells and in this way promote their functional adaptation to time of day and their survival. To fulfill this function they act on melatonin receptor type 1 (MT1 receptors) and dopamine D4 receptors (D4 receptors), respectively. The aim of the present study was to screen transcriptional regulators important for retinal physiology and/or pathology (Dbp, Egr-1, Fos, Nr1d1, Nr2e3, Nr4a1, Pgc-1α, Rorβ) for circadian regulation and dependence on melatonin signaling/MT1 receptors or dopamine signaling/D4 receptors. METHODS This was done by gene profiling using quantitative polymerase chain reaction in mice deficient in MT1 or D4 receptors. RESULTS The data obtained determined Pgc-1α and Nr4a1 as transcriptional targets of circadian melatonin and dopamine signaling, respectively. CONCLUSIONS The results suggest that Pgc-1α and Nr4a1 represent candidate genes for linking circadian neurohormone release with functional adaptation and healthiness of retina and photoreceptor cells.
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Affiliation(s)
- Stefanie Kunst
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany 2Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Tanja Wolloscheck
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Debra K Kelleher
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Uwe Wolfrum
- Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - S Anna Sargsyan
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - P Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Kenkichi Baba
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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34
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Abstract
PURPOSE Previous studies have reported the presence of a circadian rhythm in PERIOD2::LUCIFERASE (PER2::LUC) bioluminescence in mouse photoreceptors, retina, RPE, and cornea. Melatonin (MLT) modulates many physiological functions in the eye and it is believed to be one of the key circadian signals within the eye. The aim of the present study was to investigate the regulation of the PER2::LUC circadian rhythm in mouse cornea and to determine the role played by MLT. METHODS Corneas were obtained from PER2::LUC mice and cultured to measure bioluminescence rhythmicity in isolated tissue using a Lumicycle or CCD camera. To determine the time-dependent resetting of the corneal circadian clocks in response to MLT or IIK7 (a melatonin type 2 receptor, MT2, agonist) was added to the cultured corneas at different times of the day. We also defined the location of the MT2 receptor within different corneal layers using immunohistochemistry. RESULTS A long-lasting bioluminescence rhythm was recorded from cultured PER2::LUC cornea and PER2::LUC signal was localized to the corneal epithelium and endothelium. MLT administration in the early night delayed the cornea rhythm, whereas administration of MLT at late night to early morning advanced the cornea rhythm. Treatment with IIK7 mimicked the MLT phase-shifting effect. Consistent with these results, MT2 immunoreactivity was localized to the corneal epithelium and endothelium. CONCLUSIONS Our work demonstrates that MLT entrains the PER2::LUC bioluminescence rhythm in the cornea. Our data indicate that the cornea may represent a model to study the molecular mechanisms by which MLT affects the circadian clock.
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35
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Gianesini C, Clesse D, Tosini G, Hicks D, Laurent V. Unique Regulation of the Melatonin Synthetic Pathway in the Retina of Diurnal Female Arvicanthis ansorgei (Rodentia). Endocrinology 2015; 156:3292-308. [PMID: 26153723 DOI: 10.1210/en.2015-1267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Knowledge about melatonin synthesis and its potential roles within the retina remains fragmented, especially in mammals where studies have focused on the penultimate enzyme of melatonin synthesis arylalkylamine N-acetyltransferase (AA-NAT), whereas the final enzyme necessary for melatonin production is hydroxyindole-O-methytransferase (HIOMT). We explored multiple parameters of the melatonin synthetic pathway in the cone-rich retina of a diurnal rodent, Arvicanthis ansorgei, cones being previously implicated as probable reservoirs of melatonin production. We analyzed the temporal and spatial expression of Aa-nat mRNA and AA-NAT protein and enzymatic activity of AA-NAT, HIOMT, as well as the melatonin receptor type 1 and melatonin itself. We report that Aa-nat mRNA was localized principally to cones and ganglion cells (retinal ganglion cell [RGC]) with opposing cyclic expression, being maximal in cones during the night, and maximal in RGC in the daytime. AA-NAT protein was also immunolocalized to these same populations, and was present and active throughout the 24-hour period. HIOMT immunolocalization mirrored that of AA-NAT, but expression levels and activity were extremely low and remained uniform throughout the 24-hour period. MT1 showed a complementary expression pattern to the synthetic enzymes, present in rod photoreceptors, some inner retinal neurons and RGC. Surprisingly, melatonin levels were consistently low throughout the day/night cycle, in accordance with the low activity levels of HIOMT. These data demonstrate that the melatonin synthetic pathway in a diurnal rodent differs from that described for other tissues and species (nocturnal and diurnal), the contrasting phase expression in photoreceptors and RGC, suggesting distinct roles in these populations.
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Affiliation(s)
- Coralie Gianesini
- Centre National de la Recherche Scientifique Unité Propre de Recherche 3212 (C.G., D.H., V.L.), Institute for Cellular and Integrative Neurosciences, F-67084 Strasbourg, France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 7364 (D.C.), Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, Faculté de Psychologie, F-67000 Strasbourg, France; and Department of Pharmacology and Toxicology (G.T.), Morehouse School of Medicine, Atlanta, Georgia 30110
| | - Daniel Clesse
- Centre National de la Recherche Scientifique Unité Propre de Recherche 3212 (C.G., D.H., V.L.), Institute for Cellular and Integrative Neurosciences, F-67084 Strasbourg, France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 7364 (D.C.), Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, Faculté de Psychologie, F-67000 Strasbourg, France; and Department of Pharmacology and Toxicology (G.T.), Morehouse School of Medicine, Atlanta, Georgia 30110
| | - Gianluca Tosini
- Centre National de la Recherche Scientifique Unité Propre de Recherche 3212 (C.G., D.H., V.L.), Institute for Cellular and Integrative Neurosciences, F-67084 Strasbourg, France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 7364 (D.C.), Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, Faculté de Psychologie, F-67000 Strasbourg, France; and Department of Pharmacology and Toxicology (G.T.), Morehouse School of Medicine, Atlanta, Georgia 30110
| | - David Hicks
- Centre National de la Recherche Scientifique Unité Propre de Recherche 3212 (C.G., D.H., V.L.), Institute for Cellular and Integrative Neurosciences, F-67084 Strasbourg, France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 7364 (D.C.), Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, Faculté de Psychologie, F-67000 Strasbourg, France; and Department of Pharmacology and Toxicology (G.T.), Morehouse School of Medicine, Atlanta, Georgia 30110
| | - Virginie Laurent
- Centre National de la Recherche Scientifique Unité Propre de Recherche 3212 (C.G., D.H., V.L.), Institute for Cellular and Integrative Neurosciences, F-67084 Strasbourg, France; Centre National de la Recherche Scientifique Unité Mixte de Recherche 7364 (D.C.), Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg, Faculté de Psychologie, F-67000 Strasbourg, France; and Department of Pharmacology and Toxicology (G.T.), Morehouse School of Medicine, Atlanta, Georgia 30110
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Evans JA, Suen TC, Callif BL, Mitchell AS, Castanon-Cervantes O, Baker KM, Kloehn I, Baba K, Teubner BJW, Ehlen JC, Paul KN, Bartness TJ, Tosini G, Leise T, Davidson AJ. Shell neurons of the master circadian clock coordinate the phase of tissue clocks throughout the brain and body. BMC Biol 2015; 13:43. [PMID: 26099272 PMCID: PMC4489020 DOI: 10.1186/s12915-015-0157-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/16/2015] [Indexed: 11/18/2022] Open
Abstract
Background Daily rhythms in mammals are programmed by a master clock in the suprachiasmatic nucleus (SCN). The SCN contains two main compartments (shell and core), but the role of each region in system-level coordination remains ill defined. Herein, we use a functional assay to investigate how downstream tissues interpret region-specific outputs by using in vivo exposure to long day photoperiods to temporally dissociate the SCN. We then analyze resulting changes in the rhythms of clocks located throughout the brain and body to examine whether they maintain phase synchrony with the SCN shell or core. Results Nearly all of the 17 tissues examined in the brain and body maintain phase synchrony with the SCN shell, but not the SCN core, which indicates that downstream oscillators are set by cues controlled specifically by the SCN shell. Interestingly, we also found that SCN dissociation diminished the amplitude of rhythms in core clock gene and protein expression in brain tissues by 50–75 %, which suggests that light-driven changes in the functional organization of the SCN markedly influence the strength of rhythms in downstream tissues. Conclusions Overall, our results reveal that body clocks receive time-of-day cues specifically from the SCN shell, which may be an adaptive design principle that serves to maintain system-level phase relationships in a changing environment. Further, we demonstrate that lighting conditions alter the amplitude of the molecular clock in downstream tissues, which uncovers a new form of plasticity that may contribute to seasonal changes in physiology and behavior. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0157-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jennifer A Evans
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233, USA.
| | - Ting-Chung Suen
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Ben L Callif
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233, USA
| | - Andrew S Mitchell
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | | | - Kimberly M Baker
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233, USA
| | - Ian Kloehn
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, 53233, USA
| | - Kenkichi Baba
- Department of Pharmacology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Brett J W Teubner
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA, 30302, USA.,Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - J Christopher Ehlen
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Ketema N Paul
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Timothy J Bartness
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA, 30302, USA
| | - Gianluca Tosini
- Department of Pharmacology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
| | - Tanya Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, MA, 01002, USA
| | - Alec J Davidson
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, 30310, USA
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Hiragaki S, Baba K, Coulson E, Kunst S, Spessert R, Tosini G. Melatonin signaling modulates clock genes expression in the mouse retina. PLoS One 2014; 9:e106819. [PMID: 25203735 PMCID: PMC4159264 DOI: 10.1371/journal.pone.0106819] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 08/01/2014] [Indexed: 12/11/2022] Open
Abstract
Previous studies have shown that retinal melatonin plays an important role in the regulation of retinal daily and circadian rhythms. Melatonin exerts its influence by binding to G-protein coupled receptors named melatonin receptor type 1 and type 2 and both receptors are present in the mouse retina. Earlier studies have shown that clock genes are rhythmically expressed in the mouse retina and melatonin signaling may be implicated in the modulation of clock gene expression in this tissue. In this study we determined the daily and circadian expression patterns of Per1, Per2, Bmal1, Dbp, Nampt and c-fos in the retina and in the photoreceptor layer (using laser capture microdissection) in C3H-f+/+ and in melatonin receptors of knockout (MT1 and MT2) of the same genetic background using real-time quantitative RT-PCR. Our data indicated that clock and clock-controlled genes are rhythmically expressed in the retina and in the photoreceptor layer. Removal of melatonin signaling significantly affected the pattern of expression in the retina whereas in the photoreceptor layer only the Bmal1 circadian pattern of expression was affected by melatonin signaling removal. In conclusion, our data further support the notion that melatonin signaling may be important for the regulation of clock gene expression in the inner or ganglion cells layer, but not in photoreceptors.
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Affiliation(s)
- Susumu Hiragaki
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Kenkichi Baba
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Elise Coulson
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Stefanie Kunst
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Rainer Spessert
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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Tosini G, Owino S, Guillaume JL, Jockers R. Understanding melatonin receptor pharmacology: latest insights from mouse models, and their relevance to human disease. Bioessays 2014; 36:778-87. [PMID: 24903552 PMCID: PMC4151498 DOI: 10.1002/bies.201400017] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Melatonin, the neuro-hormone synthesized during the night, has recently seen an unexpected extension of its functional implications toward type 2 diabetes development, visual functions, sleep disturbances, and depression. Transgenic mouse models were instrumental for the establishment of the link between melatonin and these major human diseases. Most of the actions of melatonin are mediated by two types of G protein-coupled receptors, named MT1 and MT2 , which are expressed in many different organs and tissues. Understanding the pharmacology and function of mouse MT1 and MT2 receptors, including MT1 /MT2 heteromers, will be of crucial importance to evaluate the relevance of these mouse models for future therapeutic developments. This review will critically discuss these aspects, and give some perspectives including the generation of new mouse models.
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Affiliation(s)
- Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA, USA
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McMahon DG, Iuvone PM, Tosini G. Circadian organization of the mammalian retina: from gene regulation to physiology and diseases. Prog Retin Eye Res 2013; 39:58-76. [PMID: 24333669 DOI: 10.1016/j.preteyeres.2013.12.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 11/27/2013] [Accepted: 12/01/2013] [Indexed: 01/27/2023]
Abstract
The retinal circadian system represents a unique structure. It contains a complete circadian system and thus the retina represents an ideal model to study fundamental questions of how neural circadian systems are organized and what signaling pathways are used to maintain synchrony of the different structures in the system. In addition, several studies have shown that multiple sites within the retina are capable of generating circadian oscillations. The strength of circadian clock gene expression and the emphasis of rhythmic expression are divergent across vertebrate retinas, with photoreceptors as the primary locus of rhythm generation in amphibians, while in mammals clock activity is most robust in the inner nuclear layer. Melatonin and dopamine serve as signaling molecules to entrain circadian rhythms in the retina and also in other ocular structures. Recent studies have also suggested GABA as an important component of the system that regulates retinal circadian rhythms. These transmitter-driven influences on clock molecules apparently reinforce the autonomous transcription-translation cycling of clock genes. The molecular organization of the retinal clock is similar to what has been reported for the SCN although inter-neural communication among retinal neurons that form the circadian network is apparently weaker than those present in the SCN, and it is more sensitive to genetic disruption than the central brain clock. The melatonin-dopamine system is the signaling pathway that allows the retinal circadian clock to reconfigure retinal circuits to enhance light-adapted cone-mediated visual function during the day and dark-adapted rod-mediated visual signaling at night. Additionally, the retinal circadian clock also controls circadian rhythms in disk shedding and phagocytosis, and possibly intraocular pressure. Emerging experimental data also indicate that circadian clock is also implicated in the pathogenesis of eye disease and compelling experimental data indicate that dysfunction of the retinal circadian system negatively impacts the retina and possibly the cornea and the lens.
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Affiliation(s)
- Douglas G McMahon
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - P Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, USA; Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Gianluca Tosini
- Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, 30310 GA, USA.
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Baba K, Benleulmi-Chaachoua A, Journé AS, Kamal M, Guillaume JL, Dussaud S, Gbahou F, Yettou K, Liu C, Contreras-Alcantara S, Jockers R, Tosini G. Heteromeric MT1/MT2 melatonin receptors modulate photoreceptor function. Sci Signal 2013; 6:ra89. [PMID: 24106342 DOI: 10.1126/scisignal.2004302] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The formation of G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) heteromers enables signaling diversification and holds great promise for improved drug selectivity. Most studies of these oligomerization events have been conducted in heterologous expression systems, and in vivo validation is lacking in most cases, thus questioning the physiological significance of GPCR heteromerization. The melatonin receptors MT1 and MT2 exist as homomers and heteromers when expressed in cultured cells. We showed that melatonin MT1/MT2 heteromers mediated the effect of melatonin on the light sensitivity of rod photoreceptors in mice. This effect of melatonin involved activation of the heteromer-specific phospholipase C and protein kinase C (PLC/PKC) pathway and was abolished in MT1(-/-) or MT2(-/-) mice, as well as in mice overexpressing a nonfunctional MT2 mutant that interfered with the formation of functional MT1/MT2 heteromers in photoreceptor cells. Not only does this study establish an essential role of melatonin receptor heteromers in retinal function, it also provides in vivo support for the physiological importance of GPCR heteromerization. Thus, the MT1/MT2 heteromer complex may provide a specific pharmacological target to improve photoreceptor function.
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Affiliation(s)
- Kenkichi Baba
- 1Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, GA 30310, USA
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41
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Dortch-Carnes J, Tosini G. Melatonin receptor agonist-induced reduction of SNP-released nitric oxide and cGMP production in isolated human non-pigmented ciliary epithelial cells. Exp Eye Res 2012. [PMID: 23201027 DOI: 10.1016/j.exer.2012.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The present study was designed to determine the effects of melatonin and its receptor agonists on SNP-released nitric oxide (NO) and cGMP production in aqueous humor producing cells of the ciliary body because these effects may play a role in melatonin receptor-mediated regulation of intraocular pressure (IOP). NO release protocols were carried out using human non-pigmented ciliary epithelial (hNPCE) cells treated in dye free DMEM containing l-arginine (10(-3) M). The cGMP experimental protocols were performed using dye free DMEM containing 3-isobutyl-1-methylxanthine (IBMX, 10(-4) M). The effects of varying concentrations (10(-13), 10(-11), 10(-9), 10(-7), and 10(-5) M) of melatonin, 5-MCA-NAT (putative MT(3) agonist), N-butanoyl-2-(2-methoxy-6H-isoindolo[2, 1-a]indol-11-yl)ethanamine (IIK7; selective MT(2) agonist) or S-27633-1 (selective MT(1) agonist) on sodium nitroprusside (SNP)-released NO or cGMP production were determined in separate experiments. NO and cGMP levels were measured using a colorimetric assay or enzyme immunoassay (EIA), respectively. Melatonin receptor selectivity was evaluated using luzindole (LUZ; nonselective MT(1)/MT(2) antagonist) or 4-phenyl-2-propionamidotetralin (4P-PDOT; selective MT(2) antagonist). Melatonin, 5-MCA-NAT, and IIK7 all caused concentration-dependent reduction of SNP-released NO and cGMP production. The inhibitory actions of melatonin, 5-MCA-NAT and IIK7 were either completely blocked at 10(-13), 10(-11), and 10(-9) M concentrations of the agonists or partially at 10(-7) and 10(-5) M in the presence of luzindole or 4P-PDOT. Results from this study suggest that melatonin and its analogs, 5-MCA-NAT and IIK7 inhibit SNP-released NO and cGMP production via activation of MT(2) receptors in human NPCE cells. These actions may play a role in melatonin agonist-induced regulation of aqueous humor secretion and IOP.
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Affiliation(s)
- Juanita Dortch-Carnes
- Department of Pharmacology and Toxicology Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA 30310-1495, USA.
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Tosini G, Baba K, Hwang CK, Iuvone PM. Melatonin: an underappreciated player in retinal physiology and pathophysiology. Exp Eye Res 2012; 103:82-9. [PMID: 22960156 DOI: 10.1016/j.exer.2012.08.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 12/14/2022]
Abstract
In the vertebrate retina, melatonin is synthesized by the photoreceptors with high levels of melatonin at night and lower levels during the day. Melatonin exerts its influence by interacting with a family of G-protein-coupled receptors that are negatively coupled with adenylyl cyclase. Melatonin receptors belonging to the subtypes MT(1) and MT(2) have been identified in the mammalian retina. MT(1) and MT(2) receptors are found in all layers of the neural retina and in the retinal pigmented epithelium. Melatonin in the eye is believed to be involved in the modulation of many important retinal functions; it can modulate the electroretinogram (ERG), and administration of exogenous melatonin increases light-induced photoreceptor degeneration. Melatonin may also have protective effects on retinal pigment epithelial cells, photoreceptors and ganglion cells. A series of studies have implicated melatonin in the pathogenesis of age-related macular degeneration, and melatonin administration may represent a useful approach to prevent and treat glaucoma. Melatonin is used by millions of people around the world to retard aging, improve sleep performance, mitigate jet lag symptoms, and treat depression. Administration of exogenous melatonin at night may also be beneficial for ocular health, but additional investigation is needed to establish its potential.
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Affiliation(s)
- Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA.
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Abstract
N-Acetylserotonin (NAS) is a naturally occurring chemical intermediate in biosynthesis of melatonin. Previous studies have shown that NAS has different brain distribution patterns from those of serotonin and melatonin, suggesting that NAS might have functions other than as a precursor or metabolite of melatonin. Indeed, several studies have now shown that NAS may play an important role in mood regulation and may have antidepressant activity. Additional studies have shown that NAS stimulates proliferation of neuroprogenitor cells and prevents some of the negative effects of sleep deprivation. It is believed that the antidepressant and neurotrophic actions of NAS are due at least in part to the capability on this molecule to activate the TrkB receptor in a brain-derived neurotrophic factor-independent manner. Emerging evidence also indicates that NAS and its derivatives have neuroprotective properties and protect retinal photoreceptor cells from light-induced degeneration. In this review, the authors discuss the literature about this exciting and underappreciated molecule.
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Sengupta A, Baba K, Mazzoni F, Pozdeyev NV, Strettoi E, Iuvone PM, Tosini G. Localization of melatonin receptor 1 in mouse retina and its role in the circadian regulation of the electroretinogram and dopamine levels. PLoS One 2011; 6:e24483. [PMID: 21915336 PMCID: PMC3168505 DOI: 10.1371/journal.pone.0024483] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 08/11/2011] [Indexed: 11/30/2022] Open
Abstract
Melatonin modulates many important functions within the eye by interacting with a family of G-protein-coupled receptors that are negatively coupled with adenylate cyclase. In the mouse, Melatonin Receptors type 1 (MT1) mRNAs have been localized to photoreceptors, inner retinal neurons, and ganglion cells, thus suggesting that MT1 receptors may play an important role in retinal physiology. Indeed, we have recently reported that absence of the MT1 receptors has a dramatic effect on the regulation of the daily rhythm in visual processing, and on retinal cell viability during aging. We have also shown that removal of MT1 receptors leads to a small (3–4 mmHg) increase in the level of the intraocular pressure during the night and to a significant loss (25–30%) in the number of cells within the retinal ganglion cell layer during aging. In the present study we investigated the cellular distribution in the C3H/f+/+ mouse retina of MT1 receptors using a newly developed MT1 receptor antibody, and then we determined the role that MT1 signaling plays in the circadian regulation of the mouse electroretinogram, and in the retinal dopaminergic system. Our data indicate that MT1 receptor immunoreactivity is present in many retinal cell types, and in particular, on rod and cone photoreceptors and on intrinsically photosensitive ganglion cells (ipRGCs). MT1 signaling is necessary for the circadian rhythm in the photopic ERG, but not for the circadian rhythm in the retinal dopaminergic system. Finally our data suggest that the circadian regulation of dopamine turnover does not drive the photopic ERG rhythm.
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Affiliation(s)
- Anamika Sengupta
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Kenkichi Baba
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Francesca Mazzoni
- Istituto di Neuroscience, Consiglio Nazionale delle Ricerche, Pisa, Italy
| | - Nikita V. Pozdeyev
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Enrica Strettoi
- Istituto di Neuroscience, Consiglio Nazionale delle Ricerche, Pisa, Italy
| | - P. Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Gianluca Tosini
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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Alcantara-Contreras S, Baba K, Tosini G. Removal of melatonin receptor type 1 increases intraocular pressure and retinal ganglion cells death in the mouse. Neurosci Lett 2011; 494:61-4. [PMID: 21362461 DOI: 10.1016/j.neulet.2011.02.056] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 01/19/2011] [Accepted: 02/22/2011] [Indexed: 11/18/2022]
Abstract
Previous studies have demonstrated that melatonin is effective in lowering intraocular pressure and that it may also protect ganglion cells. We have recently reported that, in mice lacking the melatonin receptors type 1, 25-30% ganglion cells die out by 18months of age, suggesting that these receptors might be important for ganglion cells survival. In this study we show that the loss of ganglion cells is specific for melatonin receptors type 1 knock-out since mice lacking the melatonin receptors type 2 did not show any significant change in the number ganglion cells during aging. Furthermore, we report that melatonin receptors type 1 knock-out mice have higher intraocular pressure during the nocturnal hours than control or melatonin receptors type 2 knock-out mice at 3 and 12months of age. Finally, our data indicate that administration of exogenous melatonin in wild-type, but not in melatonin receptors type 1 knock-out, can significantly reduce intraocular pressure. Our studies indicate that the decreased viability of ganglion cells observed in melatonin receptors type 1 knock-out mice may be a consequence of the increases in the nocturnal intraocular pressure thus suggesting that intraocular pressure levels at night and melatonin signaling should be considered as risk factor in the pathogenesis of glaucoma.
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Affiliation(s)
- Susana Alcantara-Contreras
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute and Department of Pharmacology & Toxicology, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30130, United States
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Baba K, Sengupta A, Tosini M, Contreras-Alcantara S, Tosini G. Circadian regulation of the PERIOD 2::LUCIFERASE bioluminescence rhythm in the mouse retinal pigment epithelium-choroid. Mol Vis 2010; 16:2605-11. [PMID: 21151601 PMCID: PMC3000237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 12/02/2010] [Indexed: 11/21/2022] Open
Abstract
PURPOSE The retinal pigment epithelium (RPE) plays an important role in the maintenance of the health and function of photoreceptors. Previous studies have shown that the RPE is also involved in the regulation of disc shedding, a process that is vital for photoreceptor health. This process has been shown to be under circadian control, although the mechanisms that control it are poorly understood. The aim of the present study was to investigate Period 2 (Per2) mRNA levels in the mouse RPE in vivo, and to determine whether the cultured RPE-choroid from PERIOD 2::LUCIFERASE (PER2::LUC) knockin mice expresses a circadian rhythm in bioluminescence. METHODS Per2 mRNA levels were measured using real-time quantitative RT-PCR, and bioluminescence was measured in PER2::LUC knockin mice using a Lumicycle®. RESULTS Per2 mRNA levels in the RPE-choroid show a clear circadian rhythm in vivo. A circadian rhythm in PER2::LUC bioluminescence was recorded from cultured RPE-choroid explants. Light exposure during the subjective night did not cause a circadian rhythm phase-shift of PER2::LUC bioluminescence. Finally, removal of the suprachiasmatic nuclei of the hypothalamus did not affect the bioluminescence circadian rhythm in the RPE-choroid. CONCLUSIONS Our results demonstrate that the RPE-choroid contains a circadian clock, and the regulation of this circadian rhythm resides within the eye. These new data indicate that it may be useful to design studies with the aim of elucidating the molecular mechanisms responsible for the regulation of the rhythmic event in the RPE.
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Abstract
The incidence of obesity, insulin resistance, and type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Emerging experimental evidence suggests that the hormone melatonin plays an important role in the regulation of glucose metabolisms. In this study, we report that removal of melatonin receptor type 1 (MT1) significantly impairs the ability of mice to metabolize glucose and such inability is probably due to an increased insulin resistance in these mice. Our data suggest that MT1 receptors are implicated in the pathogenesis of T2D and open the door for a detailed exploration on the mechanisms by which MT1 receptors signaling may affect glucose metabolism.
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Pinotti M, Bertolucci C, Frigato E, Branchini A, Cavallari N, Baba K, Contreras-Alcantara S, Ehlen JC, Bernardi F, Paul KN, Tosini G. Chronic sleep deprivation markedly reduces coagulation factor VII expression. Haematologica 2010; 95:1429-32. [PMID: 20418241 DOI: 10.3324/haematol.2010.022475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Chronic sleep loss, a common feature of human life in industrialized countries, is associated to cardiovascular disorders. Variations in functional parameters of coagulation might contribute to explain this relationship. By exploiting the mouse model and a specifically designed protocol, we demonstrated that seven days of partial sleep deprivation significantly decreases (-30.5%) the thrombin generation potential in plasma evaluated upon extrinsic (TF/FVIIa pathway) but not intrinsic activation of coagulation. This variation was consistent with a decrease (-49.8%) in the plasma activity levels of factor VII (FVII), the crucial physiologicalal trigger of coagulation, which was even more pronounced at the liver mRNA level (-85.7%). The recovery in normal sleep conditions for three days completely restored thrombin generation and FVII activity in plasma. For the first time, we demonstrate that chronic sleep deprivation on its own reduces, in a reversible manner, the FVII expression levels, thus influencing the TF/FVIIa activation pathway efficiency.
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Affiliation(s)
- Mirko Pinotti
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr, Atlanta, GA 30310, USA
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Abstract
The circadian clock is an evolutionarily, highly conserved feature of most organisms. This internal timing mechanism coordinates biochemical, physiological and behavioral processes to maintain synchrony with the environmental cycles of light, temperature and nutrients. Several studies have shown that light is the most potent cue used by most organisms (humans included) to synchronize daily activities. In mammals, light perception occurs only in the retina; three different types of photoreceptors are present within this tissue: cones, rods and the newly discovered intrinsically photosensitive retinal ganglion cells (ipRGCs). Researchers believe that the classical photoreceptors (e.g., the rods and the cones) are responsible for the image-forming vision, whereas the ipRGCs play a key role in the non-image forming vision. This non-image-forming photoreceptive system communicates not only with the master circadian pacemaker located in the suprachiasmatic nuclei of the hypothalamus, but also with many other brain areas that are known to be involved in the regulation of several functions; thus, this non-image forming system may also affect several aspects of mammalian health independently from the circadian system.
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Affiliation(s)
- Ketema N Paul
- Circadian Rhythms and Sleep Disorders Program, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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Baba K, Pozdeyev N, Mazzoni F, Contreras-Alcantara S, Liu C, Kasamatsu M, Martinez-Merlos T, Strettoi E, Iuvone PM, Tosini G. Melatonin modulates visual function and cell viability in the mouse retina via the MT1 melatonin receptor. Proc Natl Acad Sci U S A 2009; 106:15043-8. [PMID: 19706469 PMCID: PMC2736407 DOI: 10.1073/pnas.0904400106] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Indexed: 11/18/2022] Open
Abstract
A clear demonstration of the role of melatonin and its receptors in specific retinal functions is lacking. The present study investigated the distribution of MT1 receptors within the retina, and the scotopic and photopic electroretinograms (ERG) and retinal morphology in wild-type (WT) and MT1 receptor-deficient mice. MT1 receptor transcripts were localized in photoreceptor cells and in some inner retinal neurons. A diurnal rhythm in the dark-adapted ERG responses was observed in WT mice, with higher a- and b-wave amplitudes at night, but this rhythm was absent in mice lacking MT1 receptors. Injection of melatonin during the day decreased the scotopic response threshold and the amplitude of the a- and b-waves in the WT mice, but not in the MT1(-/-) mice. The effects of MT1 receptor deficiency on retinal morphology was investigated at three different ages (3, 12, and 18 months). No differences between MT1(-/-) and WT mice were observed at 3 months of age, whereas at 12 months MT1(-/-) mice have a significant reduction in the number of photoreceptor nuclei in the outer nuclear layer compared with WT controls. No differences were observed in the number of cells in inner nuclear layer or in ganglion cells at 12 months of age. At 18 months, the loss of photoreceptor nuclei in the outer nuclear layer was further accentuated and the number of ganglion cells was also significantly lower than that of controls. These data demonstrate the functional significance of melatonin and MT1 receptors in the mammalian retina and create the basis for future studies on the therapeutic use of melatonin in retinal degeneration.
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MESH Headings
- Adaptation, Biological
- Aging
- Animals
- Cell Survival
- Darkness
- Electroretinography
- Gene Expression Regulation
- Melatonin/metabolism
- Mice
- Mice, Knockout
- RNA, Messenger/genetics
- Receptor, Melatonin, MT1/deficiency
- Receptor, Melatonin, MT1/genetics
- Receptor, Melatonin, MT1/metabolism
- Retina/cytology
- Retina/metabolism
- Retinal Degeneration/metabolism
- Retinal Degeneration/therapy
- Vision, Ocular
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Affiliation(s)
- Kenkichi Baba
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | - Nikita Pozdeyev
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, GA 30322; and
| | - Francesca Mazzoni
- Istituto di Neuroscience, Consiglio Nazionale delle Ricerche, Pisa 56100, Italy
| | | | - Cuimei Liu
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | - Manami Kasamatsu
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | | | - Enrica Strettoi
- Istituto di Neuroscience, Consiglio Nazionale delle Ricerche, Pisa 56100, Italy
| | - P. Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, GA 30322; and
| | - Gianluca Tosini
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
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